Add API to get FrameSize of a window.

native/Avalonia.Native/src/OSX/window.mm

@@ -202,6 +202,21 @@ virtual HRESULT GetClientSize(AvnSize* ret) override
         }
     }
 
+    virtual HRESULT GetFrameSize(AvnSize* ret) override
+    {
+        @autoreleasepool
+        {
+            if(ret == nullptr)
+                return E_POINTER;
+
+            auto frame = [Window frame];
+            ret->Width = frame.size.width;
+            ret->Height = frame.size.height;
+
+            return S_OK;
+        }
+    }
+
     virtual HRESULT GetScaling (double* ret) override
     {
         @autoreleasepool

src/Android/Avalonia.Android/Platform/SkiaPlatform/TopLevelImpl.cs

@@ -55,6 +55,8 @@ public virtual Point GetAvaloniaPointFromEvent(MotionEvent e, int pointerIndex)
 
         public virtual Size ClientSize => Size.ToSize(RenderScaling);
 
+        public Size? FrameSize => null;
+
         public IMouseDevice MouseDevice { get; } = new MouseDevice();
 
         public Action Closed { get; set; }

src/Avalonia.Controls/ApiCompatBaseline.txt

@@ -12,4 +12,6 @@ EnumValuesMustMatch : Enum value 'Avalonia.Platform.ExtendClientAreaChromeHints
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platform.ITopLevelImpl.SetCursor(Avalonia.Platform.ICursorImpl)' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platform.ITopLevelImpl.SetCursor(Avalonia.Platform.IPlatformHandle)' is present in the contract but not in the implementation.
 MembersMustExist : Member 'public void Avalonia.Platform.ITopLevelImpl.SetCursor(Avalonia.Platform.IPlatformHandle)' does not exist in the implementation but it does exist in the contract.
-Total Issues: 13
+InterfacesShouldHaveSameMembers : Interface member 'public System.Nullable<Avalonia.Size> Avalonia.Platform.ITopLevelImpl.FrameSize' is present in the implementation but not in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Nullable<Avalonia.Size> Avalonia.Platform.ITopLevelImpl.FrameSize.get()' is present in the implementation but not in the contract.
+Total Issues: 15

src/Avalonia.Controls/Embedding/Offscreen/OffscreenTopLevelImpl.cs

@@ -35,6 +35,8 @@ public Size ClientSize
             }
         }
 
+        public Size? FrameSize => null;
+
         public double RenderScaling
         {
             get { return _scaling; }

src/Avalonia.Controls/Platform/ITopLevelImpl.cs

@@ -22,6 +22,11 @@ public interface ITopLevelImpl : IDisposable
         /// </summary>
         Size ClientSize { get; }
 
+        /// <summary>
+        /// Gets the total size of the toplevel, excluding shadows.
+        /// </summary>
+        Size? FrameSize { get; }
+
         /// <summary>
         /// Gets the scaling factor for the toplevel. This is used for rendering.
         /// </summary>

src/Avalonia.Controls/TopLevel.cs

@@ -42,6 +42,12 @@ public abstract class TopLevel : ContentControl,
         public static readonly DirectProperty<TopLevel, Size> ClientSizeProperty =
             AvaloniaProperty.RegisterDirect<TopLevel, Size>(nameof(ClientSize), o => o.ClientSize);
 
+        /// <summary>
+        /// Defines the <see cref="FrameSize"/> property.
+        /// </summary>
+        public static readonly DirectProperty<TopLevel, Size?> FrameSizeProperty =
+            AvaloniaProperty.RegisterDirect<TopLevel, Size?>(nameof(FrameSize), o => o.FrameSize);
+
         /// <summary>
         /// Defines the <see cref="IInputRoot.PointerOverElement"/> property.
         /// </summary>
@@ -74,6 +80,7 @@ public abstract class TopLevel : ContentControl,
         private readonly IPlatformRenderInterface _renderInterface;
         private readonly IGlobalStyles _globalStyles;
         private Size _clientSize;
+        private Size? _frameSize;
         private WindowTransparencyLevel _actualTransparencyLevel;
         private ILayoutManager _layoutManager;
         private Border _transparencyFallbackBorder;
@@ -161,6 +168,7 @@ public TopLevel(ITopLevelImpl impl, IAvaloniaDependencyResolver dependencyResolv
             styler?.ApplyStyles(this);
 
             ClientSize = impl.ClientSize;
+            FrameSize = impl.FrameSize;
 
             this.GetObservable(PointerOverElementProperty)
                 .Select(
@@ -197,6 +205,15 @@ public Size ClientSize
             protected set { SetAndRaise(ClientSizeProperty, ref _clientSize, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the total size of the window.
+        /// </summary>
+        public Size? FrameSize
+        {
+            get { return _frameSize; }
+            protected set { SetAndRaise(FrameSizeProperty, ref _frameSize, value); }
+        }
+
         /// <summary>
         /// Gets or sets the <see cref="WindowTransparencyLevel"/> that the TopLevel should use when possible.
         /// </summary>
@@ -366,6 +383,7 @@ protected virtual void HandleClosed()
         protected virtual void HandleResized(Size clientSize)
         {
             ClientSize = clientSize;
+            FrameSize = PlatformImpl.FrameSize;
             Width = clientSize.Width;
             Height = clientSize.Height;
             LayoutManager.ExecuteLayoutPass();

src/Avalonia.Controls/WindowBase.cs

@@ -222,6 +222,7 @@ protected override void HandleClosed()
         protected override void HandleResized(Size clientSize)
         {
             ClientSize = clientSize;
+            FrameSize = PlatformImpl.FrameSize;
             LayoutManager.ExecuteLayoutPass();
             Renderer?.Resized(clientSize);
         }

src/Avalonia.DesignerSupport/Remote/Stubs.cs

@@ -21,6 +21,7 @@ class WindowStub : IWindowImpl, IPopupImpl
         public IPlatformHandle Handle { get; }
         public Size MaxAutoSizeHint { get; }
         public Size ClientSize { get; }
+        public Size? FrameSize => null;
         public double RenderScaling { get; } = 1.0;
         public double DesktopScaling => 1.0;
         public IEnumerable<object> Surfaces { get; }

src/Avalonia.Headless/HeadlessWindowImpl.cs

@@ -41,6 +41,7 @@ public void Dispose()
         }
 
         public Size ClientSize { get; set; }
+        public Size? FrameSize => null;
         public double RenderScaling { get; } = 1;
         public double DesktopScaling => RenderScaling;
         public IEnumerable<object> Surfaces { get; }

src/Avalonia.Native/WindowImplBase.cs

@@ -104,6 +104,20 @@ public Size ClientSize
             }
         }
 
+        public Size? FrameSize
+        {
+            get
+            {
+                if (_native != null)
+                {
+                    var s = _native.FrameSize;
+                    return new Size(s.Width, s.Height);
+                }
+
+                return default;
+            }
+        }
+
         public IEnumerable<object> Surfaces => new[] {
             (_gpu ? _glSurface : (object)null),
             this 

src/Avalonia.Native/avn.idl

@@ -435,6 +435,7 @@ interface IAvnWindowBase : IUnknown
      HRESULT Close();
      HRESULT Activate();
      HRESULT GetClientSize(AvnSize*ret);
+     HRESULT GetFrameSize(AvnSize*ret);
      HRESULT GetScaling(double*ret);
      HRESULT SetMinMaxSize(AvnSize minSize, AvnSize maxSize);
      HRESULT Resize(double width, double height);

src/Avalonia.X11/X11Window.cs

@@ -297,6 +297,30 @@ void UpdateSizeHints(PixelSize? preResize)
 
         public Size ClientSize => new Size(_realSize.Width / RenderScaling, _realSize.Height / RenderScaling);
 
+        public Size? FrameSize
+        {
+            get
+            {
+                XGetWindowProperty(_x11.Display, _handle, _x11.Atoms._NET_FRAME_EXTENTS, IntPtr.Zero,
+                    new IntPtr(4), false, (IntPtr)Atom.AnyPropertyType, out var _,
+                    out var _, out var nitems, out var _, out var prop);
+
+                if (nitems.ToInt64() != 4)
+                {
+                    // Window hasn't been mapped by the WM yet, so can't get the extents.
+                    return null;
+                }
+
+                var data = (IntPtr*)prop.ToPointer();
+                var extents = new Thickness(data[0].ToInt32(), data[2].ToInt32(), data[1].ToInt32(), data[3].ToInt32());
+                XFree(prop);
+
+                return new Size(
+                    (_realSize.Width + extents.Left + extents.Right) / RenderScaling,
+                    (_realSize.Height + extents.Top + extents.Bottom) / RenderScaling);
+            }
+        }
+
         public double RenderScaling
         {
             get
@@ -589,6 +613,13 @@ public WindowState WindowState
 
         private void OnPropertyChange(IntPtr atom, bool hasValue)
         {
+            if (atom == _x11.Atoms._NET_FRAME_EXTENTS)
+            {
+                // Occurs once the window has been mapped, which is the earliest the extents
+                // can be retrieved, so invoke event to force update of TopLevel.FrameSize.
+                Resized.Invoke(ClientSize);
+            }
+
             if (atom == _x11.Atoms._NET_WM_STATE)
             {
                 WindowState state = WindowState.Normal;

src/Linux/Avalonia.LinuxFramebuffer/FramebufferToplevelImpl.cs

@@ -62,6 +62,7 @@ public void SetCursor(ICursorImpl cursor)
         }
 
         public Size ClientSize => ScaledSize;
+        public Size? FrameSize => null;
         public IMouseDevice MouseDevice => new MouseDevice();
         public IPopupImpl CreatePopup() => null;
 

src/Windows/Avalonia.Win32.Interop/Wpf/WpfTopLevelImpl.cs

@@ -100,6 +100,7 @@ public void Dispose()
         }
 
         Size ITopLevelImpl.ClientSize => _finalSize;
+        Size? ITopLevelImpl.FrameSize => null;
         IMouseDevice ITopLevelImpl.MouseDevice => _mouse;
 
         double ITopLevelImpl.RenderScaling => PresentationSource.FromVisual(this)?.CompositionTarget?.TransformToDevice.M11 ?? 1;

src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs

@@ -745,6 +745,26 @@ public enum WindowsMessage : uint
             WM_DISPATCH_WORK_ITEM = WM_USER,
         }
 
+        public enum DwmWindowAttribute : uint
+        {
+            DWMWA_NCRENDERING_ENABLED = 1,
+            DWMWA_NCRENDERING_POLICY,
+            DWMWA_TRANSITIONS_FORCEDISABLED,
+            DWMWA_ALLOW_NCPAINT,
+            DWMWA_CAPTION_BUTTON_BOUNDS,
+            DWMWA_NONCLIENT_RTL_LAYOUT,
+            DWMWA_FORCE_ICONIC_REPRESENTATION,
+            DWMWA_FLIP3D_POLICY,
+            DWMWA_EXTENDED_FRAME_BOUNDS,
+            DWMWA_HAS_ICONIC_BITMAP,
+            DWMWA_DISALLOW_PEEK,
+            DWMWA_EXCLUDED_FROM_PEEK,
+            DWMWA_CLOAK,
+            DWMWA_CLOAKED,
+            DWMWA_FREEZE_REPRESENTATION,
+            DWMWA_LAST
+        };
+
         public enum MapVirtualKeyMapTypes : uint
         {
             MAPVK_VK_TO_VSC = 0x00,
@@ -1388,6 +1408,9 @@ public static extern IntPtr CreateFileMapping(IntPtr hFile,
         [DllImport("dwmapi.dll")]
         public static extern int DwmExtendFrameIntoClientArea(IntPtr hwnd, ref MARGINS margins);
 
+        [DllImport("dwmapi.dll")]
+        public static extern int DwmGetWindowAttribute(IntPtr hwnd, int dwAttribute, out RECT pvAttribute, int cbAttribute);
+
         [DllImport("dwmapi.dll")]
         public static extern int DwmIsCompositionEnabled(out bool enabled);
 

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -213,6 +213,21 @@ public Size ClientSize
             }
         }
 
+        public Size? FrameSize
+        {
+            get
+            {
+                if (DwmIsCompositionEnabled(out var compositionEnabled) != 0 || !compositionEnabled)
+                {
+                    GetWindowRect(_hwnd, out var rcWindow);
+                    return new Size(rcWindow.Width, rcWindow.Height) / RenderScaling;
+                }
+
+                DwmGetWindowAttribute(_hwnd, (int)DwmWindowAttribute.DWMWA_EXTENDED_FRAME_BOUNDS, out var rect, Marshal.SizeOf(typeof(RECT)));
+                return new Size(rect.Width, rect.Height) / RenderScaling;
+            }
+        }
+
         public IScreenImpl Screen { get; }
 
         public IPlatformHandle Handle { get; private set; }

src/iOS/Avalonia.iOS/AvaloniaView.cs

@@ -91,6 +91,7 @@ public void SetTransparencyLevelHint(WindowTransparencyLevel transparencyLevel)
             }
 
             public Size ClientSize => new Size(_view.Bounds.Width, _view.Bounds.Height);
+            public Size? FrameSize => null;
             public double RenderScaling => _view.ContentScaleFactor;
             public IEnumerable<object> Surfaces { get; set; }
             public Action<RawInputEventArgs> Input { get; set; }